Abstract

Thirty six onshore basins in Queensland, Australia, have been assessed for their CO2 geological storage prospectivity through injection into either: regional reservoir-seal intervals (‘saline reservoirs‘ and aquifers); depleted oil and gas fields; or deep unmineable coal seams. This comprehensive state wide regional assessment is based on the technical (geological) suitability for geological storage, and does not consider factors such as potential interference with other resources, distance from emissions nodes or absolute storage volumes. Basins were assessed by evaluating the potential reservoir-seal intervals for their effectiveness for injection, storage and containment of CO2. Methodologies have been developed that allow the estimation of storage capacity volumes within highly prospective reservoir-seal fairways at a regional scale. These estimates reflect conservative values that are more reliable than previous theoretical estimates, which relied upon access to pore space at the physical limit of the pore rock volume to accept fluids. Results show that the greatest potential to store the large quantities of CO2 required to make deep cuts in Queensland’s stationary emissions is to use deep, regional reservoir-seal intervals using structural traps or migration assisted storage (MAS) mechanisms. The Bowen, Cooper, Eromanga, Galilee and Surat basins contain Paleozoic–Mesozoic age fluvial reservoirs that have either produced hydrocarbons, and/or are major aquifers, and are evaluated as having the highest prospectivity for CO2 geological storage in Queensland. Other basins have either low prospectivity or are unsuitable for geological storage. Depleted oil and gas fields and deep unmineable coal seams provide only limited opportunities for geological storage of CO2 in Queensland.